Puffer interrupter with downstream initiated arc

ABSTRACT

The movable contact of a puffer type interrupter is movably connected to the nozzle of the puffer breaker so that, when the contacts of the puffer breaker separate, the arc is initiated downstream of the nozzle throat and thereafter the nozzle and contact move relative to one another to place the contact upstream of the nozzle throat and to a position which maximizes the interruption operation of the breaker.

United States Patent [191 McConnell et al.

[451 Oct. 21, 1975 1 PUFFER INTERRUPTER WITH DOWNSTREAM INITIATED ARC .lnventors: Lorne D. McConnell, Chalfont;

Hansruedi Aumayer, Harleysville, both of Pa.

I-.T-E Imperial Corporation, Spring House, Pa.

Filed: May 2, 1974 Appl. No.: 466,408

Assignee:

US. Cl. 200/148 A; 200/148 A Int. Cl. H01H 33/70 Field of Search 200/148 A, 148 R, 148 B,

References Cited UNITED STATES PATENTS 6/1973 Noeske 200/148 A 10/1973 Leeds 200/148 A 8/1974 Zukler 200/184 A Primary ExaminerRobert S. Macon Attorney, Agen't, 0r FirmOstrolenk, Faber, Gerb & Soffen [57] ABSTRACT 6 Claims, 6 Drawing Figures US. Patent r; ig--4- 1 z I I PUFFER INTERRUPTER WITH DOWNSTREAM I INITIATED ARC BACKGROUND OF THE INVENTION This invention relates to puffer type circuit interrupters, and more specifically relates to a novel arrangement whereby the movable contact of a puffer type interrupter is flexibly connected to a gas directing nozzle so that the are between the separating interrupter contacts is initially drawn downstream of the nozzle, with the movable contact later returning to its preferred upstream position within the nozzle after the initial arcing operation.

Single pressure'SF type puffer interrupters are well known in the art and commonly comprise a pair of separable contacts which are contained within a sealed container filled with sulfur hexafluoride gas or the like. One of the contacts is normally fixed to a nozzleshaped member which encloses the area of engagement between the two cooperating contacts. The movable contact is connected to a piston andcylinder arrangement such that, when the movable contact moves to a disengaged position, the piston and cylinder force gas flow through the nozzle and through the region at which the contacts separate. This then provides a temporarily high-pressure region which moves gas through the arcing region to assist in the extinction of the are drawn between the separating contacts and to sweep the space between the separating contacts clear of ionized products.

In order to obtain interruption in this type breaker, two conditions must be satisfied:

l. The opening stroke of the movable contact must be sufficient toestablish an open gap large enough to withstand the crest of the system recovery voltage; and

- 2. the opening stroke must develop a sufficient pressure differential across the nozzle to provide effective sweeping and deionization of the arc space.

During the opening stroke of the movable contact, it is also desirable to keep the energy released in the arc space to a minimum and to release this energy in such a manner as to minimize its effect on the interior components and to minimize the forces necessary to operate the interrupter.

In puffer interrupters of this type, it is common practice to fix a movable contact to the nozzle so that both move relative to a stationary contact, and further to fix the end of the movable contact at some fixed and preferred location which is upstream of the interrupter nozzle throat. The arc which is drawn between the separating contacts in such a device is then initiated upstream of the nozzle and will be drawn through the nozzle throat during the first part of the opening stroke.

Duringthe opening stroke and as pointedout above, the arc produces various types of arcing products and ionized gas in ,the region which is upstream of the nozzle so that these product's and ionized gases must be swept free :if interruption is to be obtained. Moreover, the arc and, heated gases produced by the arcare immediatelyadjacent to the nozzle andthe nozzle throat, thereby causing thermal deterioration of :the nozzle which can reduce the interrupting lifetime of the device.

I A further disadvantage of the fixed positioningzof the movable contact upstream of the nozzle throat isthat the initial arc which is drawn will cause a high-pressure zone in the nozzle throat which results in a back pressure which must be overcome by higher operating forces from the operating mechanism. Note further that the back pressure in the nozzle can result momentarily in a back flow of gas so that arc products could be brought into the puffer piston area.

BRIEF SUMMARY OF THE INVENTION In accordance with the invention, the movable contact and the movable nozzle are movably connected to one another and the movable contact is normally biased to a preferred location slightly upstream of the nozzle throat. However, upon operation of the interrupter, the movable contact and nozzle move relative to one another so that the end of the movable contact is downstream of the nozzle throat at the time an arc is initiated between the separating contacts. Following the initial arcing interval, the movable contact returns to its preferred upstream location relative to the nozzle, when a sufficiently large open gap is formed'to withstand the crest of the system recovery voltage and enough pressure has developed to product effective are sweeping action.

- The arrangement of the present invention permits release of energy during the initial arcing period in a region which is downstream of the nozzle, so that pressure release can be affected through the relatively open gap between the nozzle wall and the fixed contact as well as through the hollow fixed contact if such an arrangement is used. Thus, the undesirable effects on the nozzle of upstream reverse flow and early contamination of the nozzle throat are largely overcome.

There is also a reduction of total energy release by eliminating or reducing gas blast in the early part of the opening stroke (when interruption cannot be effected) so that are voltage and thus are energy can be kept lower. There is also a reduction of the swept volume necessary in the puffer piston due to the elimination of the need to clear away initial upstream are products which reach the piston region and a reduction of useless gas flow when the contact gap is too small to effect an eruption. That is to say, the actual time at which contact separation occurs may be slightly delayed while the nozzle moves relative to the contact and toward a position in which the contact is downstream of the nozzle throat. This same time delay also allows time for a gas pressure differential to build to a sufficiently high value to enable interruption of the are when the contacts open. A further advantage obtained by the invention is an improvement in capacitor switching performance by minimizing the possibility of interruption of the arc while the contacts are still very close together so that restrike is more probable.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a portion of an inte'rrupter which incorporates the present invention,

with the contacts in their closed position and wherein the nozzle is fixed to the operating rod while the movable contact is flexibly connected to the operating rod.

FIG. 2 shows the interrupter of FIG. 1 immediately after the contacts have separated, with the separating contacts being downstream of the nozzle throat.

FIG. 3 shows the interrupter of FIGS. 1 and 2, with the contacts in their fully open position.

FIG. 4 shows a second embodiment of the invention in cross-sectional view wherein the stationary contact is fixed to the operating rod, while the nozzle is flexibly connected to the operating rod.

FIG. 5 shows the interrupter of FIG. 4 just after the contacts have separated, with the initial are being formed at a location downstream of the nozzle throat.

FIG. 6 shows the embodiment of FIGS. 3 and 4 after the contacts are fully opened and the nozzle is retracted to effect a greater open gap distance.

DETAILED DESCRIPTION OF THE DRAWINGS Referring first to FIGS. 1, 2 and 3, there is shown a portion of a puffer breaker which includes a stationary conductive piston 10 which can be connected to a first terminal 11 of the breaker. The member 10 may be contained within a suitable housing shown schematically by the dotted block 12, which is filled with sulfur hexafluoride at some positive pressure. Other gases and gas mixtures could also be used if desired.

A conductive operating rod 13 then terminates in an enlarged head 14 which may be segmented if desired, and is in sliding engagement-with movable contact cylinder 15. The movable contact cylinder 15 may be segmented into fingers at its right-hand end, where the fingers engage the stationary tubular contact 16. Operating rod 13 is then electrically connected to the stationary conductive member 10 by suitable sliding contact members 17.

The conductive member 15 may then terminate in an annular disk-shaped end region 18 and may have arcing contact finger type elements 19 at its right-hand end which engage the arcing contact end of stationary contact 16. Movable contact 15 is then supported within an insulation cup 20 which extends from disk 21 which is fixed to the interior of the bafi'le cylinder or nozzle 22. The baffle cylinder 22 then consists of a cylindrical body 23 having a restricted nozzle throat 24 where baffle cylinder 23 is slidable on the stationary member 10 which serves as a stationary piston for the puffer interrupter.

The disk 21 then has a plurality of openings including openings 25 and 26 therein which permit the flow of gas from the volume between disk 21 and member 10 to flow to the right and through the nozzle throat 24 when the circuit breaker is opened as will be later described.

A sliding seal 30 may be provided between stationary member 10 and cylindrical portion 23 of nozzle 22 if desired. A biasing spring is then captured within insulation cup 20 and biases contact cylinder 15 to the left and into its seat in the plate 21. Note that the movable components of the breaker are all connected to one another and consist of the operating rod 13, plate 21 and baffle 22. These components move as a single unit when operating forces are applied to the operating rod 13.

In order to move contact 15 to the right and toward its engaged position, the left-hand end of contact 15 is picked up by the plate 21 and is driven to the right with the operating rod 13. In order to move the contact to its open position, the operating rod 13 moves to the left.

The operation of the interrupter shown in FIG. 1 is as follows:

The contacts are shown in their normally closed position in FIG. 1. In order to open the breaker, the operating rod 13 is moved to the left. The initial movement of operating rod 13 and of disk 21 and nozzle 22 to the left is independent of-the. movement of ,contact 15 which is held in "position sincethejfrictional engagement forces between inwardly turned contact end 19 and the stationary contact 16 are greater than the initial force from spring 35-.

When the movable contacts reach the position of FIG. 2, the spring 35 has been compressed to a point where it is able to. overcome the engagement forces between contact 15 and stationary contact 16, and the region of contact disengagement isnow downstream of the nozzle throat 24. Consequently, as the contacts separate in FIG. 2, the initialarcing is downstream of the nozzle throat 24 resulting in low-arc energy and minimum pressure effect upstream of the nozzle. It should be-further noted-that the pressure created by the initial downstream arc will bear against surface 40 of throat 24, therebyto provide, a pressure assist in the movement of the movable components to. the left during the opening of the breaker.- The vspring 35 accelerates contact 15 to the left, thereby increasing the effective speed with which a contact gap is achieved. Furthermore, the contact 15 blocks nozzle 40 toeliminate gas flow and pressure loss before the contacts reach a point where effective interruption canbe obtained. 1

As the moving components continue to move to the left,the movable contact ultimately reaches the pre- 'in'vention'which differs from the embodiments of FIGS.

1, 2 and 3 in that the relatively movable components in FIGS. 4 to 6 is the nozzle portion of the movable system rather than the contact portion of the movable system as in FIGS. 1, 2 and 3. I

Referring now 'to FIGSL4, '5 and 6, the puffer interrupter consists of a fixed puffer piston 50 which may be of conductive material and which slidably receives a puffer cylinder 51 which is fixed to the movable contact operating rod 52 by the plate 53. Note that plate 53 is similar to plate 21 of FIGS. 1, 2 and 3 and contains suitable openings,'such as openings 54 and 55 which permit the flow of gas into the interrupting area upon the movement of the pufi'er cylinder 51 to the left. The moving contact rod 52 may then be electrically connected to the conductive piston 50 by transfer contacts 56 and one terminal of the breakermay be connected tothefpuffer piston 50 andis shown as the terminal 57. The right-hand end of the contact operating rod 52 then carries a segmented movable contact member 60 whichcooperates with a stationary contact tube 61 which defines the, second terminal 62 of the breaker.

The contacts 60 and 61 are then surrounded by nozzle '63 which is flexibly carried on the puffer cylinder by the compression spring 70.which.- is disposed between the inwardly tumed flange 71 of cylinder 51 and the outwardly turned flange 72of nozzle 63. Note that nozzle 63, like nozzle 22 of FIGS. 1 2 and 3, is of any desired insulation material. Y v

The-operation of .the system of FIGS.'4 to 6 is as follows: I 1

In order to open the breaker, the operating rod 52 is initially moved to the left from the position of FIG. 4 toward the position of FIG. 5. At this time the movable operating rod 52, plate 53, cylinder 51 and nozzle 63 move as a unit to the left and the throat of the nozzle 63 moves with contact fingers 60. During this time, the major portion of the nozzle throat is generally downstream of the contact region at which initial arcing will take place when the position of FIG. 2 is reached. The contact 60 is substantially blocking gas flow through the nozzle 63, thus promoting early build-up of pressure upstream of the contacts.

Once the position of FIG. 2 is reached, a pressure within nozzle 63 and against interior surface 63a has been reached tomove the nozzle 63 to the dotted-line position which is the interrupting position for the nozzle and for the system. However, this position is not assumed until sufficient internal pressure has been produced to ensure effective are interruption and clearing of are products from the interruption space. At the same time, the nozzle is moved to its interrupting position only after a suitable interrupting gap has been reached between the contacts 60 and 61. Thus, the initial arcing will be downstream of the nozzle to result in minimum pressure effects upstream of the nozzle while the initial interrupting position is reached with all components in their preferred position to obtain effective permanent interruption.

Note further that, if there is extensive downstream pressure which is arc-generated on surface 63b of nozzle 63, this excess pressure will prevent the nozzle 63 from moving to its position in FIG. 5 until a sufficient pressure differential is developed across the nozzle throat to permit effective interruption. After the interruption operation, the nozzle 63 is spring-retracted to the position shown in FIG. 6 with the contacts in their fully open position.

Although this invention has been described with respect to its preferred embodiments, it should be understood that many. variations and modifications will now be obvious to those skilled in the art, and it is preferred, therefore, that the scope of the invention be limited not by the specific disclosure herein, but only by the appended claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. In a puffer type circuit interrupter; said puffer type circuit interrupter including a stationary elongated contact; a movable contact movable between an engaged and disengaged position with said stationary contact; an insulation nozzle surrounding said movable and stationary contacts, an operating rod connected to said nozzle and to said movable contact, a pistoncylinder means connected to said operating rod for producing a flow of gas through said nozzle and through the arc space produced by the separation of said movable and stationary contacts; a housing surrounding said contacts, said nozzle, and said pistoncylinder means and filled with a relatively high dielectric gas; said nozzle having an internal nozzle throat restriction; said nozzle and said movable contact being movable relative to one another; and biasing means normally biasing said nozzle and said movable contact to a position wherein the end of said movable contact is downstream of said nozzle throat restriction; and

means for moving said end of said movable contact downstream of said nozzle throat restriction at a time following the initial movement of said movable contact to its disengaged position, whereby the initial arcing space between said movable and stationary contacts occurs upstream of said nozzle throat restriction, and whereby said arcing space is thereafter disposed downstream of said nozzle throat restriction and is swept free of arcing products by gas flow from said piston-cylinder means and through said nozzle throat restriction; said movable contact, said stationary contact and said nozzle each being coaxially disposed and each being generally axially elongated; said movable contact being fixed to said operating rod; said nozzle being flexibly mounted on said operating rod and being axially movable with respect thereto.-

2. In a puffer type circuit interrupter; said puffer type circuit interrupter including a stationary elongated contact; a movable contact movable between an engaged and disengaged position with said stationary contact; an insulation nozzle surrounding said movable and stationary contacts, an operating rod connected to said nozzle and to said movable contact, a pistoncylinder means connected to said operating rod for producing a flow of gas through said nozzle and through the arc space produced by the separation of said movable and stationary contacts; a housing surrounding said contacts, said nozzle, and said pistoncylinder means and filled with a relatively high dielectric gas; said nozzle having an internal nozzle throat restriction; said nozzle and said movable contact being movable relative to one another; and biasing means normally biasing said nozzle and said movable contact to a position wherein the end of said movable contact is downstream of said nozzle throat restriction; and means for moving said end of said movable contact downstream of said nozzle throat restriction at a time following the initial movement of said movable contact to its disengaged position, whereby the initial arcing space between said movable and stationary contacts occurs upstream of said nozzle throat restriction, and whereby said arcing space is thereafter disposed downstream of said nozzle throat restriction and is swept free of arcing products by gas flow from said piston-cylinder means and through said nozzle throat restriction; said movable contact, said stationary contact and said nozzle each being coaxially disposed and each being generally axially elongated; said nozzle being fixed to said stationary contact; said movable contact being flexibly mounted on said operating rod and being axially movable with respect thereto.

3. The puffer circuit interrupter of claim 1 wherein said piston-cylinder means includes a piston fixed to said operating rod and coaxially disposed with said rod.

4. The puffer circuit interrupter of claim 3 wherein said dielectric gas is sulfur hexafluoride.

5. The puffer circuit interrupter of claim 4 wherein said movable contact is fixed to said operating rod, and wherein said nozzle is flexibly mounted on said operating rod and is axially movable with respect thereto.

6. The puffer circuit interrupter of claim 4 wherein said nozzle is fixed to said stationary contact, and wherein said movable contact is flexibly mounted on said operating rod and is axially movable with respect thereto. 

1. In a puffer type circuit interrupter; said puffer type circuit interrupter including a stationary elongated contact; a movable contact movable between an engaged and disengaged position with said stationary contact; an insulation nozzle surrounding said movable and stationary contacts, an operating rod connected to said nozzle and to said movable contact, a piston-cylinder means connected to said operating rod for producing a flow of gas through said nozzle and through the arc space produced by the separation of said movable and stationary contacts; a housing surrounding said contacts, said nozzle, and said piston-cylinder means and filled with a relatively high dielectric gas; said nozzle having an internal nozzle throat restriction; said nozzle and said movable contact being movable relative to one another; and biasing means normally biasing said nozzle and said movable contact to a position wherein the end of said movable contact is downstream of said nozzle throat restriction; and means for moving said end of said movable contact downstream of said nozzle throat restriction at a time following the initial movement of said movable contact to its disengaged position, whereby the initial arcing space between said movable and stationary contacts occurs upstream of said nozzle throat restriction, and whereby said arcing space is thereafter disposed downstream of said nozzle throat restriction and is swept free of arcing products by gas flow from said piston-cylinder means and through said nozzle throat restriction; said movable contact, said stationary contact and said nozzle each being coaxially disposed and each being generally axially elongated; said movable contact being fixed to said operating rod; said nozzle being flexibly mounted on said operating rod and being axially movable with respect thereto.
 2. In a puffer type circuit interrupter; said puffer type circuit interrupter including a stationary elongated contact; a movable contact movable between an engaged and disengaged position with said stationary contact; an insulation nozzle surrounding said movable and stationary contacts, an operating rod connected to said nozzle and to said movable contact, a piston-cylinder means connected to said operating rod for producing a flow of gas through said nozzle and through the arc space produced by the separation of said movable and stationary contacts; a housing surrounding said contacts, said nozzle, and said piston-cylinder means and filled with a relatively high dielectric gas; said nozzle having an internal nozzle throat restriction; said nozzle and said movable contact being movable relative to one another; and biasing means normally biasing said nozzle and said movable contact to a position wherein the end of said movable contact is downstream of said nozzle throat restriction; and means for moving said end of said movable contact downstream of said nozzle throat restriction at a time following the initial movement of said movable contact to its disengaged position, whereby the initial arcing space between said movable and stationary contacts occurs upstream of said nozzle throat restriction, and whereby said arcing space is thereafter disposed downstream of said nozzle throat restriction and is swept free of arcing products by gas flow from said piston-cylinder means and through said nozzle throat restriction; said movable contact, saId stationary contact and said nozzle each being coaxially disposed and each being generally axially elongated; said nozzle being fixed to said stationary contact; said movable contact being flexibly mounted on said operating rod and being axially movable with respect thereto.
 3. The puffer circuit interrupter of claim 1 wherein said piston-cylinder means includes a piston fixed to said operating rod and coaxially disposed with said rod.
 4. The puffer circuit interrupter of claim 3 wherein said dielectric gas is sulfur hexafluoride.
 5. The puffer circuit interrupter of claim 4 wherein said movable contact is fixed to said operating rod, and wherein said nozzle is flexibly mounted on said operating rod and is axially movable with respect thereto.
 6. The puffer circuit interrupter of claim 4 wherein said nozzle is fixed to said stationary contact, and wherein said movable contact is flexibly mounted on said operating rod and is axially movable with respect thereto. 